The present invention is generally related to optical devices, systems, and methods, and in one embodiment provides a fluid lens capable of being adjusted in spherical and/or cylindrical power so as to allow, for example, correction of refractive errors of the human eye.
Refractive errors of the human eye are measured in a variety of ways, including both subjective and objective approaches. Subjective measurements of the eye may be made by placing corrective lenses or a corrective optical system before the eye and conducting a controlled test of the resulting corrected vision. These eye tests are commonly used to identify a sphero-cylindrical correction that provides improved vision to a subject while that subject is reviewing a suitable target image.
When conducting subjective refraction measurements, a series of individual trial lenses may be positioned before the eye of the test subject. In many subjective refraction tests, the subject looks through a phoropter, an instrument having a bank of lenses. The lenses of the phoropter can be positioned sequentially in front of the eye, with the subject often choosing between two or more alternative lens arrangements so as to provide the most improved visual acuity. Although some modern phoropters have motorized mechanisms that move or select the lenses, most remain manual devices.
In addition to the subjective measurements of human refractive errors, there are a variety of structures intended to produce objective measurements of the human eye. Objective measurements may be made by a variety of automatic refractors, for example. These instruments often have variable correcting optical trains that can correct either spherical errors alone, or that can correct sphero-cylindrical errors of the eye throughout an adjustment range. Automatic refractors alter the spherical (and often the cylindrical) power of an optical train using motors, gears, slides, bearings, pulleys, and/or the like. These moving components tend to make automatic refractors complex, bulky, susceptible to wear and damage, and quite expensive.
In light of the above, it would be advantageous to provide improved optical devices, systems, and methods. It would be particularly beneficial if these improvements allowed adjustment, correction, and/or measurement of spherical, cylindrical, toroidal, and possibly other errors, particularly for measurement of errors of the human eye. It would be particularly advantageous if these improvements could be realized without relying on a large number of alternative lenses and without the motors, gears, slides, bearings, pulleys, and other moving parts of known eye measurement systems.